<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>盒子阴影</title>
</head>
<body>

<style>
    div{
        margin: 0px auto;
        width: 200px;
        height: 200px;
        border: 10px solid red;
        box-shadow:   50px 50px 50px chartreuse;
    }
</style>
<div>

</div>
</body>
</html>